System and Method for Wireless Communications Measurements and CSI Feedback

ABSTRACT

Measurements and Channel State Information (CSI) feedback are configured using communications between a network and user equipment (UE). The communications includes a first signaling from a network component to the UE indicating one or more reference signal (RS) resource configurations, a second signaling indicating one or more interference measurement (IM) resource configurations, and a third signaling indicating a CSI report configuration, wherein the CSI report configuration indicates a subset of the one or more RS resource configurations and a subset of the one or more IM resource configurations. The UE establishes a RS based measurement according to the subset of the one or more RS resource configurations and an IM according to the subset of the one or more IM resource configurations. The UE then generates and sends to the network a CSI report in accordance with the CSI report configuration and using the RS based measurement and the IM.

This application is a continuation of U.S. Non-Provisional applicationSer. No. 14/632,881 filed on Feb. 26, 2015 entitled “System and Methodfor Wireless Communications Measurements and CSI Feedback,” which is acontinuation of U.S. Non-Provisional application Ser. No. 13/732,129filed on Dec. 31, 2012 entitled “System and Method for WirelessCommunications Measurements and CSI Feedback,” now U.S. Pat. No.9,008,585 issued Apr. 14, 2015, which claims the benefit of U.S.Provisional Application No. 61/592,417 filed on Jan. 30, 2012, all ofwhich are hereby incorporated herein by reference as if reproduced intheir entireties.

TECHNICAL FIELD

The present invention relates to the field of wireless communications,and, in particular embodiments, to a system and method for configuringwireless communications measurements and CSI feedback.

BACKGROUND

Present and future wireless communication systems include LTE, LTE-A andLTE-A-beyond systems. Measurements and Channel State Information (CSI)feedback are one focus area in LTE-A studies. Measurements and CSIfeedback are typically based on various reference signals (RSs). Indownlink transmission of LTE-A system, there are reference signals forUE to perform channel/signal estimation/measurements for demodulation ofPhysical downlink control channel (PDCCH) and other common channels, aswell as for some measurements and feedbacks. The reference signalsinclude the Common/Cell-specific Reference Signal (CRS) inherited fromthe Rel-8/9 specification of E-UTRA. A dedicated/de-modulation referencesignal (DMRS) can be transmitted together with the Physical downlinkshared channel (PDSCH) in Rel-10 of E-UTRA. The DMRS is used for channelestimation during PDSCH de-modulation.

In Rel-10, Channel Status Indication Reference Signal (CSI-RS) isintroduced in addition to CRS and DMRS. CSI-RS is used for Rel-10 UEs tomeasure the channel status, e.g., for multiple antennas cases.PMI/CQI/RI and other feedbacks may be based on the measurement of CSI-RSfor Rel-10 and beyond UE. The PMI is the precoding Matrix indicator, andthe CQI is channel quantity indicator, and the RI is rank indicator ofthe precoding matrix. The CSI-RS in Rel-10 can support up to 8transmission antennas while the CRS can only support up to 4transmission antennas in Rel-8/9. The number of CSI-RS antenna ports canbe 1, 2, 4, or 8. In addition, to support the same number of antennaports, the CSI-RS has less overhead due to its low density in time andfrequency.

SUMMARY

In accordance with an embodiment, a method implemented by a userequipment (UE) comprises receiving from a network a first signalingindicating one or more reference signal (RS) resource configurations,receiving from the network a second signaling indicating one or moreinterference measurement (IM) resource configurations, and receivingfrom the network a third signaling indicating a channel stateinformation (CSI) report configuration, wherein the CSI reportconfiguration indicates a subset of the one or more RS resourceconfigurations and a subset of the one or more IM resourceconfigurations.

In another embodiment, a UE configured for wireless communicationsmeasurements and CSI feedback comprises a processor and a computerreadable storage medium storing programming for execution by theprocessor. The programming including instructions to receive from anetwork a first signaling indicating one or more RS resourceconfigurations, receive from the network a second signaling indicatingone or more IM resource configurations, and receive from the network athird signaling indicating a CSI report configuration, wherein the CSIreport configuration indicates a subset of the one or more RS resourceconfigurations and a subset of the one or more IM resourceconfigurations.

In another embodiment, a method implemented by a network component forconfiguring a UE for wireless communications measurements and CSIfeedback comprises transmitting to the UE a first signaling indicatingone or more RS resource configurations, transmitting to the UE a secondsignaling indicating one or more IM resource configurations, andtransmitting to the UE a third signaling indicating a CSI reportconfiguration, wherein the CSI report configuration indicates a subsetof the one or more RS resource configurations and a subset of the one ormore IM resource configurations.

In another embodiment, a network component for configuring a UE forwireless communications measurements and CSI feedback comprises aprocessor and a computer readable storage medium storing programming forexecution by the processor. The programming including instructions totransmit to the UE a first signaling indicating one or more RS resourceconfigurations, transmit to the UE a second signaling indicating one ormore IM resource configurations, and transmit to the UE a thirdsignaling indicating a CSI report configuration, wherein the CSI reportconfiguration indicates a subset of the one or more RS resourceconfigurations and a subset of the one or more IM resourceconfigurations.

In yet another embodiment, a method implemented by a network componentfor configuring a UE for wireless communications measurements and CSIfeedback comprises receiving from a second network component informationabout a first IM resource configuration and a second IM resourceconfiguration, wherein the first IM resource configuration is associatedwith a first transmission activity by the second network component andthe second IM resource configuration is associated with a secondtransmission activity by the second network component. The methodfurther comprises transmitting to the UE a first signaling indicatingone or more RS resource configurations, transmitting to the UE a secondsignaling indicating one or more IM resource configurations, wherein theone or more IM resource configurations include the first IM resourceconfiguration and the second IM resource configuration; and transmittingto the UE a third signaling indicating one or more CSI reportconfigurations, wherein the one or more CSI report configurationsindicate a subset of the one or more RS resource configurations and asubset of the one or more IM resource configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIG. 1 illustrates example CSI-RS patterns for two antenna ports.

FIG. 2 illustrates example CSI-RS patterns for four antenna ports.

FIG. 3 illustrates example CSI-RS patterns for eight antenna ports.

FIG. 4 illustrates an embodiment measurement and CSI configuration andfeedback method.

FIG. 5 illustrates another embodiment measurement and CSI configurationand feedback method.

FIG. 6 illustrates an embodiment cooperative multi-point (CoMP) feedbackused for resource-restricted measurements.

FIG. 7 illustrates an embodiment of two interference measurement CSI-RSconfigured for resource-restricted measurements.

FIG. 8 illustrates embodiment resource-restricted measurementsconfigured for some CoMP schemes.

FIG. 9 illustrates an embodiment reception method.

FIG. 10 is a block diagram of a processing system that can be used toimplement various embodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

In Orthogonal frequency-division multiplexing (OFDM) systems, thefrequency bandwidth is divided into multiple subcarriers in frequencydomain. In time domain, one subframe is divided into multiple OFDMsymbols. The OFDM symbol may have cyclic prefix to avoid theinter-symbol interference due to multiple path delays. One resourceelement is defined by the time-frequency resource within one subcarrierand one OFDM symbol. A reference signal and other signals, such as datachannel PDSCH and control channel PDCCH, are orthogonal and multiplexedin different resource elements in time-frequency domain. Further, thesignals are modulated and mapped into resource elements. Using inverseFourier transform per each OFDM symbol, the signals in frequency domainare transformed into the signals in time domain, and are transmittedwith added cyclic prefix to avoid the inter-symbol interference.

FIG. 1 illustrates example CSI-RS patterns 100 using OFDM symbols withnormal cyclic prefix (CP) for two antenna ports. There are 14 OFDMsymbols labeled from 0 to 13. The CSI-RS patterns 100 are signaled fromthe wireless network to a UE. The symbols 0 to 6 correspond to evenslots, and the symbols 7 to 13 correspond to odd slots. There are 12subcarriers labeled from 0 to 11. The CSI-RS patterns 100 include threepatterns that are obtain by shifts in frequency domain. Each patterncomprises a plurality of resource elements or blocks, where eachresource block corresponds to one subcarrier and one symbol. The threepatterns are indicated by different three corresponding shading patterns(two diagonal shading patterns and one diamond shading pattern). Otherpatterns with two antenna ports may also be obtained (for example in anyof the blocks with gray shading). For each pattern, number “0” indicatesa first antenna port of the UE (antenna port 0), and number “1”indicates a second antenna port of the UE (antenna port 1). FIG. 2illustrates example CSI-RS patterns 200 using OFDM symbols with normalCP for four antenna ports. For each pattern, numbers “0”, “1”, “2”, and“3” indicate four corresponding antenna ports. FIG. 3 illustratesexample CSI-RS patterns 300 using OFDM symbols with normal CP for eightantenna ports. For each pattern, numbers “0” to “7” indicate eightcorresponding antenna ports. Other CSI-RS patterns with extended CP canbe defined similarly.

The resource element of each of the patterns above may be denoted by(k′,l′) per resource block, where the pair k′ and l′ indicates thesubcarrier number and symbol number respectively in Physical resourceblock (PRB). All the CSI-RS patterns can be represented as shown inTable 1 below, where n_(s) is the slot number. The CSI-RS patterns 100,200, and 300 are signaled by the wireless network to a UE, e.g., by abase station (BS) or an E-UTRAN Node-B (eNB). The CSI-RS port number andCSI-RS configuration are also signaled to the UE via dedicated higherlayer signaling in Release 10. The number of ports is signaled using 2bits of data and the CSI-RS configuration is signaled using 5 bits ofdata.

The CSI-RS has a low density compared with the CRS. The subframe withCSI-RS transmission is defined by the duty cycle and subframe offset.For example, the duty cycle can be 5 milliseconds (ms), 10 ms, 20 ms, 40ms, or 80 ms. The cycle and subframe offset for the CSI-RS are alsosignaled to the UE via dedicate higher layer signaling in Rel-10. ARel-10 UE may assume PDSCH rate matching around the CSI-RS resourceelements (REs), after UE capability (e.g., the UE's release) is known bythe eNB or BS for all unicast PDSCH transmissions in any of theavailable transmission modes. For example, Table 1 shows that when aRel-10 UE is configured in transmission mode 9, The UE uses the CSI-RS(for 1, 2, 4, or 8 antenna ports) for CQI/PMI feedback measurement.

TABLE 1 Mapping from CSI configuration to (k′, l′) for normal cyclicprefix. Frame Number of CSI reference signals configured struc- CSI 2 48 ture Config- n_(s) n_(s) n_(s) type uration (k′, l′) mod2 (k′, l′) mod2 (k′, l′) mod 2 FS 0 (9, 5) 0 (9, 5) 0 (9, 5) 0 1 & 2 1 (11, 2)  1 (11,2)  1 (11, 2)  1 2 (9, 2) 1 (9, 2) 1 (9, 2) 1 3 (7, 2) 1 (7, 2) 1 (7, 2)1 4 (9, 5) 1 (9, 5) 1 (9, 5) 1 5 (8, 5) 0 (8, 5) 0 6 (10, 2)  1 (10, 2) 1 7 (8, 2) 1 (8, 2) 1 8 (6, 2) 1 (6, 2) 1 9 (8, 5) 1 (8, 5) 1 10 (3, 5)0 11 (2, 5) 0 12 (5, 2) 1 13 (4, 2) 1 14 (3, 2) 1 15 (2, 2) 1 16 (1, 2)1 17 (0, 2) 1 18 (3, 5) 1 19 (2, 5) 1 FS 20 (11, 1)  1 (11, 1)  1 (11,1)  1 2 only 21 (9, 1) 1 (9, 1) 1 (9, 1) 1 22 (7, 1) 1 (7, 1) 1 (7, 1) 123 (10, 1)  1 (10, 1)  1 24 (8, 1) 1 (8, 1) 1 25 (6, 1) 1 (6, 1) 1 26(5, 1) 1 27 (4, 1) 1 28 (3, 1) 1 29 (2, 1) 1 30 (1, 1) 1 31 (0, 1) 1

In accordance to the 3GPP standard, which is incorporated herein, theconfiguration of multiple non-zero-power CSI-RS resources includesconfiguring the following parameters:

(1) antennaPortsCount, resourceConfig: independently configured amongCSI-RS resources;(2) subframeConfig: whether common or independent among CSI-RSresources;(3) a configurable parameter to derive the pseudo-random sequencegenerator initialization (c_(init)): c_(init) is independentlyconfigured among CSI-RS resources as:

c _(init)=2¹⁰·(7·(n _(s)+1)+l+1)·(2·X+1)+2·X+N _(CP),

where X is configurable in a UE specific manner and may take on anyvalue in the range from 0 to 503. Other considerations include whetherRel-10 formula can be used without a change, whether beyond 503 valuesare supported, and whether CSI-RS ports always have the same scramblingor can have different scrambling within a CSI-RS resource;(4) P_(c): details of signaling can also be considered.

The CSI-RS may be interfered by the PDSCH of neighbor cells. Therefore,PDSCH RE muting is used to reduce the interference to the CSI-RS ofneighbor cell(s). The following is agreed in 3GPP regarding muting:

(1) Muting configuration is signaled via dedicated higher-layersignalling: PDSCH muting is performed over a bandwidth that follows thesame rule as the CSI-RS;(2) A UE may assume downlink CSI-RS EPRE(energy per RE) is constantacross the downlink system bandwidth and constant across all subframesuntil different CSI-RS information is received;(3) The intra-subframe location of muted resource elements is indicatedby a 16-bit bitmap: each bit corresponds to a 4-port CSI-RSconfiguration, all REs used in a 4-port CSI-RS configuration set to 1(for example) are muted (zero-power assumed at UE), except for theCSI-RS REs if they belong to this CSI-RS configuration. This signalingis common for frequency division duplexing (FDD) and time divisionduplexing (TDD) CSI-RS configurations;(4) When muting of PDSCH REs is configured: a Rel-10 UE may assume PDSCHrate matching around the muted REs (after UE capability, i.e. itsrelease, is known by the eNB) for all unicast PDSCH transmissions in anytransmission mode;(5) One value of subframe offset and duty cycle is signaled for all themuted resource elements, using the same encoding as for the subframeoffset and duty cycle of the CSI-RS: muted REs can be located insubframes either with or without CSI-RS. The subframe offset and dutycycle of the muted REs is indicated by a parameter separate from theparameter indicating the subframe offset and duty cycle of the CSI-RS.

Although muting is used to reduce the interference to CSI-RS of neighborcells, there is no direct relationship between a muting pattern in acurrent cell and CSI-RS patterns of neighbor cells. In other words, themuting pattern can be configured in a cell independently. A CSI-RSpattern is signaled to the UE by radio resource control (RRC) signalingto support up to 8 transmission antennas. The signaling can be repeatedperiodically with a duty cycle and a subframe offset. To reduce theinterference from and to the CSI-RS of neighbor cells, muting is appliedto PDSCH transmission. In other words, the PDSCH transmission isconfigured to transmit nothing in the muted resource elements indicatedby muting pattern. Signaling is sent to inform a Rel-10 UE of the mutingpattern. Hence, the Rel-10 UE discards the muted resource elements inthe reception of PDSCH. The muting pattern may be signaled by a 16 bitbitmap, where each bit represents a 4-ports CSI-RS pattern. For example,each bit is set to 1 to indicate that the 4-port CSI-RS pattern ismuted, and is set to 0 to indicate that the 4-ports CSI-RS pattern isnot muted.

Measurements and CSI feedback are one focus area in CoordinatedMulti-Points (CoMP) and Heterogeneous Network (Hetnet) studies. InRel-10, signal measurements at a UE are based on CSI-RS or CRS, andinterference measurements at a UE are based on CRS. Subsequently, CSIreports are obtained at the UE from the signal measurements andinterference measurements and fed back to the eNB. In Rel-10, only onetype of signal measurements and one type of interference measurementsare allowed. In this case, the signal from one transmission point andone interference condition are supported, with the exception ofresource-restricted measurements. With resource-restricted measurements,at most two types of interference measurements are allowed. In thiscase, up to two interference conditions are supported, and these twointerference conditions are semi-statically configured in a timedivision multiplexed (TDMed) manner over the subframes.

The measurements and CSI feedback mechanism is insufficient orunsatisfactory for Rel-11 and onward. Multiple types of signalmeasurements may be supported in order to support multiple transmissionpoints in CoMP. However, a method for flexibly supporting multiple typesof interference measurements with reasonable accuracy, overhead, andcomplexity is challenging to achieve and is highly desired. In variousembodiments herein, systems and methods for improved measurements andCSI feedback are provided. Embodiment methods include signaling aplurality of CSI resources for signal and interference measurements to aUE. The embodiment methods also include signaling a configuration ofmeasurements report to be returned by the UE. Upon receiving thesignaling of CSI resources and configuration of measurements report, theUE performs signal measurements using the indicated resources, and hencesends a measurements report or feedback in accordance with the indicatedconfiguration.

The signaling of CSI resources and configuration of measurements reportincludes a first signaling that indicates CSI resources to be used bythe UE for signal measurements, a second signaling that indicates CSIresources to be used by the UE for interference measurements, and athird signaling that indicates a CQI report configuration for the UE.The CQI report configuration may indicate indexes for linking differentCQI reports to corresponding subsets of the indicated RS resources forsignal and corresponding subsets of the indicated interferencemeasurements. The embodiments may allow relatively high flexibility ofmeasurements/CSI feedback/transmissions as well as different types oftransmission schemes that can be supported by CoMP, HetNet, and othertransmission schemes. For example, the Rel-10 almost blank subframe(ABS) based Enhanced Inter-Cell Interference Control (eICIC) can berealized by CoMP CSI feedback without resorting to traditionaltechniques used for eICIC (e.g., resource-restricted measurements). Someembodiments also allow ABS-based eICIC to be configured together withthe CoMP CSI feedback.

The three signaling components for CSI measurements and feedback forsignal/channel measurements, interference measurements, and CQIcalculation and report or feedback, are sent from the wireless networkto the UE. The signaling components may be coupled with each other,e.g., signaled at about the same time, or combined as one or twosignaling components.

The signal measurements can be based on general RS, for instance, eitherCRS or non-zero-power (NZP) CSI-RS, e.g., depending on the transmissionmode. In 3GPP LTE Rel-11, NZP CSI-RS is used for signal/channelmeasurements. In CoMP, multiple NZP CSI-RSs can be configured for eachUE to measure the signals from multiple transmitting points. Thus, thenetwork configures and signals multiple NZP CSI-RS resources to each UEfor signal measurements.

For interference measurements, CoMP transmission may require one or moretypes of interference conditions to be measured based on UE specificallyconfigured REs or CRS. In 3GPP LTE Rel-11, the candidates for UEspecifically configured CRS include NZP CSI-RS and zero-power (ZP)CSI-RS. Embodiments below generally are described for the case of NZP/ZPCSI-RS based interference measurements. However, the same concepts applyto more generic designs, such as interference measurements based on UEspecifically configured REs, including for example CSI-RS REs, part orentire CRS REs, part or entire PDSCH REs, new designed RS REs, and/orother determined REs. In general, the resource on which the interferencemeasurements are performed is called an interference measurement (IM)resource.

The interference conditions that a UE may experience in CoMP can varydynamically depending on the scheduling decision, such as in DynamicPoint Selection (DPS) or Dynamic Point Blanking (DPB). The CSI-RSresources for interference measurements for DPS (or likewise, DPB) maybe semi-statically configured and coordinated by eNBs, and they are notnecessarily tied to the PDSCH resources dynamically allocated for DPS(or DPB) transmissions. In contrast, when Rel-10 resource-restrictedmeasurements are used, up to two types of interference conditions are tobe measured, and the measurements are based on the CRS. The twointerference conditions in resource-restricted measurements correspondto two semi-statically configured subframes subsets, and the resourcesused to measure each interference condition may be located in theassociated subset. The conditions in Table 2 are observed ofinterference measurements used in CoMP CSI feedback andresource-restricted measurements.

TABLE 2 Comparison of interference measurements used in CoMP CSIfeedback and resource-restricted measurements. Interference measurementInterference conditions/ resource transmission schemes CoMP onsemi-statically configured dynamically varying REs (CSI-RS) Resource- onCRS of semi-statically semi-statically varying Restricted configuredsubframes Measurements

As shown in Table 2, the interference measurement mechanisms for CoMPschemes and schemes with resource-restricted measurements appeardifferent. However, carefully examining these two mechanisms can revealthat both require the resources used for interference measurements to besemi-statically configured and properly coordinated by eNBs. Suchresources are subject to certain restrictions so that they correspond tothe eNB-intended interference condition or interference hypothesis.Thus, it may be beneficial and feasible to focus on this commonality andprovide a common interference measurement mechanism for both CoMPschemes and semi-static coordination schemes with the capability ofmeasuring multiple interference conditions that are common in CoMP andHetNet scenarios.

In an embodiment, a common interference measurement mechanism is usedfor both CoMP schemes and semi-static coordination schemes. The commonmechanism is based on IM resources for interference measurements, which,in the special case of 3GPP LTE Rel-11, becomes the channel-stateinformation interference-measurement (CSI-IM) resource. Accordingly,each CSI-IM resource is used for measuring one interference condition,which may allow a multiple-to-one relation between the CSI-IM resourcesand the interference condition. Two CSI-RS resources may be sufficientto achieve the functionality provided by resource-restrictedmeasurements of measuring two interference conditions. More CSI-RSresources can also be used to measure more than two interferenceconditions. Therefore, the eNB configures and signals multiple CSI-RSresources for interference measurements (or CSI-IM resources, or generalIM resources)

A plurality of options may be implemented for providing the signalingfor CSI-RS based interference measurements. In a first option, thesignaling for NZP/ZP CSI-RS based interference measurements is asignaling independent of the signaling for signal measurements. Forinstance, in addition to the signaling of multiple NZP CSI-RS resourcesconfigured for signal measurements, an eNB signals multiple CSI-RS (withzero-power or non-zero-power CSI-RS) resources to each UE forinterference measurements, and the format and/or content of thesignaling may reuse or partially reuse the signaling for the NZP CSI-RSor ZP CSI-RS. In a second option, the signaling for CSI-RS basedinterference measurements is a signaling combined with other signaling,such as that for signal measurements. For instance, in addition to thedata fields in CSI-RS resources configured for signal measurements ormuting, another field is added to indicate if this CSI-RS resource isused for signal measurements, interference measurements, and/or RadioLink Monitoring (RLM)/Radio Resource Management (RRM) measurements. Thisadded field may also be an independent signaling or a part of anothersignaling (such as part of the CQI resource signaling described below).

For any of the options above, each IM resource is used for measuring oneinterference condition, or multiple IM resources can also be configuredfor measuring the same interference condition. In the latter case, theeNB(s) guarantees that these IM resources correspond to the sameinterference condition. The configured IM resources can be used formeasuring various interference conditions in CoMP and HetNet. Forexample in CoMP, one CSI-IM resource is configured and signaled tomeasure the interference from outside a CoMP set for a UE, and oneCSI-IM resource is configured and signaled to measure the interferencefrom some or all transmission points inside a CoMP set for a UE andfurther the interference outside the CoMP set for the UE. Additionally,one CSI-IM resource can be configured and signaled to measure theinterference from outside a CoMP set for a UE but some transmissionpoint(s) outside the CoMP set may be transmitting with certaininterference coordination constraints. The interference coordinationconstraints may include muting or transmitting with reduced power,transmitting with certain spatial directions to be avoided (i.e.,nulling in certain directions), or transmitting only along certaindirections.

Further, a UE may need to feedback multiple CQI reports to support CoMPschemes or resource-restricted measurements based schemes. Each CQIreport is associated with one CQI hypothesis which specifies one signalcondition and one interference condition. For each CQI report, thesignal condition is associated with one or more CSI-RS resources usedfor signal measurements, as indicated by the eNB. The support of JointTransmission (JT) may require more than one CSI-RS resources to be used.For each CQI report, the interference condition can be associated withone or more CSI-IM resources used for interference measurements, asindicated by the eNB. The UE side interference adjustments may or maynot be needed. To simplify UE implementation, the eNB configures theinterference measurements such that no UE side adjustment is needed. Toguarantee this, the eNB is configured to ensure that the CSI-IMresources used for interference measurements correspond to the same typeof interference condition.

To achieve the above conditions for each CQI report, the eNB configuresand signals the CSI-RS resources to be used for signal measurements andthe CSI-IM resources to be used for interference measurements. The UEcalculates each CQI based on the indicated CSI-RS resources and CSI-IMresources, and the eNB assumes the UE does not perform UE sideinterference or CQI adjustments. Accordingly, the interferencemeasurements and CQI calculation is based on appropriate and restrictedresources that correspond to the intended interference condition.

In an embodiment, an eNB signals a set of CQI configurations to a UE,which instructs the UE to generate and transmit the CQI reports withdetermined periods and subframe offsets according to the configurations.The CQI configurations also instructs the UE to generate each CQI reportbased on a subset of CSI-RS resources for signal measurements and asubset of CSI-IM resources for interference measurements, which are alsosignaled by the eNB as described above. The subsets of signal and/orinterference measurement resources are indicated in each CQIconfiguration signaled by the eNB. As an example, the subset correspondsto a bitmap contained in each CQI configuration signaled by the eNB. Ifa bit in the bitmap is set (or not set), then the corresponding CSI-RSresource or the corresponding CSI-IM resource is used for the CQIcomputation, which provides high flexibility of supporting a variety ofCQI hypotheses with reduced signaling overhead. In another example, therestricted resource for signal and/or interference measurement issignaled explicitly as the CSI-RS resources in each CQI configuration,which has very high flexibility at a price of much higher signalingoverhead.

In yet another example, the restricted resource for signal and/orinterference measurements is signaled by indexing in each CQIconfiguration the configured set of the CSI-RS resources. For instance,a UE receives a signaling indicating that a number of three CSI-RSresources are configured for signal measurements, which are indexed as0, 1, and 2. The UE also receives a signaling indicating that the sameor different number of CSI-IM resources are configured for interferencemeasurements, which are indexed as 0, 1, and 2 (for example in the caseof three CSI-IM resources for interference measurements). In addition,the UE receives a signaling indicating that a number of four CQIs, forexample, are to be reported. As an example, the signal includes thefollowing information specifying the measurement resources: CQI0-(0,0),CQI1 —(0,2), CQI2—(1,1), and CQI3—(2,2), where CQIn—(i,j) indicatescomputing the n-th CQI from the i-th signal measurement (based on thei-th CSI-RS resource for signal measurement) and the j-th interferencemeasurement (based on the j-th CSI-IM resource for interferencemeasurement). An advantage of this embodiment method is that thesignaling overhead may be reduced if some or all of the multiple CQIsshare a same RS resource and/or a same IM resource. Flexiblecombinations of the signaled RS resources and the signaled IM resourcesto obtain the desired CQIs are supported.

Although the above example is described as one CSI-RS resource used forsignal measurement and one CSI-IM resource used for interferencemeasurement, the signaling can indicate more than one CSI-RS resourcesused for signal measurement and more than one CSI-IM resources used forinterference measurement for generating one CQI report. This may beindicated using the format CQIn−([i₁,i₂, . . . ,i_(k)], [j₁,j₂, . . .,j_(m)]), where the i's specify signal measurement resources and the j'sspecify interference measurement resources. The signaling for CQI reportconfiguration may further indicate mathematical operations to be used bythe UE, such as, for example, adding the interference measurementassociated with j₂ to j₁, and then subtracting the interferencemeasurement associated with j₃, for which additional bits are needed inthe signaling.

In an embodiment, the eNB signals the CSI-RS for RLM/RRM measurementindependent of or combined with the signaling for CQI/PMI/RI feedbackmeasurements (including signal/channel measurements and/or interferencemeasurements). The CSI-RS for RLM/RRM may include the normal CSI-RS forRel-10 UE, the new CSI-RS for Rel-11 and/or beyond UE, or combinationsthereof. The signaling may inform the UE which antenna ports are withinone group. The RLM/RRM measurement can be reported per group of signaledantenna ports. For example, the measurement of a group of antenna portsis reported similar to the report of the measurement for the antennaports of a cell. Thus, the measurement and/or report of multiple groupsof antenna ports is obtained similar to that of the antenna ports ofmultiple cells.

Based on the RLM/RRM measurement, the eNB can signal the CSI-RS forCQI/PMI/RI feedback measurement to the UE. Hence, the signaling ofCSI-RS may be used for either CQI/PMI/RI feedback measurement or RRM/RLMmeasurement (for example, Reference signal received power (RSRP)measurement in 3GPP). The signaling of CSI-RS may include information toindicate whether the signaling is for RRM/RLM or CQI/PMI/RI.

FIG. 4 illustrates an embodiment measurement and CSI configuration andfeedback method 400 that includes some of the features described above.Initially, at step 401, the eNB signals CSI-RS resources for RLM/RRMmeasurements to the UE. At step 402, the UE receives and decodes thesignaling and then measures signals/channels on the CSI-RS resourcessignaled for RLM/RRM measurement. At step 403, the UE returns theRLM/RRM measurement(s). Next, at step 411, after receiving the RLM/RRMmeasurement(s) from the UE, the eNB signals CSI-RS resources for signalmeasurements to the UE, which then, at step 412, receives and decodesthe signaling and measures signals/channels on the CSI-RS resourcessignaled for signal measurement. At step 421, the eNB signals CSI-IMresources for interference measurements to the UE, which then, at step422, receives and decodes the signaling and measures interference on theCSI-RS resources signaled for interference measurement. At step 431, theeNB signals CQI configurations to the UE, which then, at step 432,receives and decodes the signaling and assesses the specified signalmeasurements and interference measurements. The steps 411 to 432 may beimplemented in any appropriate and logical order. At step 440, the UEgenerates the CQI reports according to the signaled CQI configurationsbased on the signaled signal measurements and interference measurements.At step 450, the UE reports the CQI reports to the eNB.

FIG. 5 illustrates another embodiment measurement and CSI configurationand feedback method 500 that includes some of the features describedabove. Initially, at step 411, the eNB signals NZP/ZP CSI-RS resourcesto the UE. At step 412, the UE receives and decodes the signaling fromthe eNB. At step 421, the eNB signals CQI configurations to the UE. Atstep 431, the UE measures signals/channels on the CSI-RS resourcessignaled for signal measurements. At step 432, the UE measuresinterference on the CSI-RS resources signaled for interferencemeasurements. At step 433, the UE assesses the specified signalmeasurements and interference measurements. At step 434, the UE measuressignals/channels on the CSI-RS resources signaled for RLM/RRMmeasurements. The steps 431 to 434 may be implemented in any appropriateand logical order. At step 440, the UE generates the CQI reportsaccording to the signaled CQI configurations.

There are several resource-restricted measurements based schemes,including eICIC or Further Enhanced Inter-Cell Interference Control(FeICIC) schemes with zero-power or reduced-power ABS, and CoordinatedBeam Blanking (CBB) which is a form of a CoMP Coordinated Scheduling(CS)/Coordinated Beam-forming (CB) scheme. Such schemes may be viewed asspecial types of CoMP schemes with semi-static coordination, andconsequently, they can use the CoMP CSI schemes described above fortheir CSI measurements and reports. In this case, the semi-staticresource-restricted measurements are not needed, since the dynamic CoMPmeasurements and feedback scheme may be sufficient. In other words,subframe-level semi-static blanking/coordination (which generallyrestricts the data transmissions, e.g. PDSCH transmissions, to besemi-statically configured in a similar pattern as measurementresources) may be replaced by CSI-RS resource level semi-staticblanking/coordination (which may allow more flexibility on datatransmissions).

For example, in ABS-based eICIC, the Pico configures the followingCSI-RS resources:

(1) One set of NZP CSI-RS to measure Pico signals;(2) One set of NZP/ZP CSI-RS for interference measurements for MacroABS. This CSI-RS is not necessarily located in the Macro ABS, since theMacro can mute on the CSI-RS REs on which the UE's interferencemeasurements are established. In other words, the Macro muting is notnecessarily done on Macro PDSCH; it may be done only on some Macro REscorresponding to the UEs interference measurements without Macrointerference. Alternatively, the Macro may simply mute on both CSI-RSREs and some or all other REs, which may effectively make the entiresubframe an ABS;(3) One set of NZP/ZP CSI-RS for interference measurements for Macronon-ABS. This CSI-RS is not necessarily located in the Macro non-ABS,since the Macro can transmit on the CSI-RS REs (generally, the UE issignaled to discard those REs) on which the UE's interferencemeasurements are established. In other words, the Macro transmission isnot necessarily Macro PDSCH transmission; the Macro transmission may beonly on some Macro REs corresponding to the UEs interferencemeasurements with Macro interference. Alternatively, the Macro maytransmit on both CSI-RS REs and some or all other REs, and thetransmission is of the same type as the desired interference conditionto Pico UEs.

If dynamic Macro-Pico coordination is allowed, then it is possible todecouple the measurements/CSI feedback and other transmissions (such asPDSCH transmissions) by utilizing the CoMP feedback schemes describedabove. Macro-Pico can dynamically decide if the Macro would blank on acertain time/frequency/spatial-domain resources as long as themeasurement resources (NZP/ZP CSI-RS) for signal and interference areconfigured and coordinated accordingly. Therefore, the requirement onsemi-statically configured ABS pattern for eICIC may be relaxed. This isenabled by CSI-RS based interference measurements and not typically withCRS based interference measurements. For the case of zero-power ABSbased solution, the dynamic interference coordination for PDSCHtransmission leads to a scheme in the DPB category. For other or moregeneral cases, the resulting schemes are not DPB.

FIG. 6 illustrates an embodiment CoMP feedback 600 that is used forresource-restricted measurements, for example over 40 subframes. Pico UEsends two CSI reports, each based on one set of CSI-RS. Dynamic eICICcan be achieved using this following mechanism. If a Macro-Pico pairdecides that the Macro mutes on certain RBs, then on those RBs, theMacro stops transmission and the Pico uses a low-interference CSI forscheduling/precoding. No subframe subsets that may restrictscheduling/transmission are needed for achieving eICIC. The CSI-RS basedinterference measurements for resource-restricted measurements can alsobe implemented, which provides higher flexibility than CRS basedinterference measurements for resource-restricted measurements.

With regard to reference resources, the resource-restricted measurementswith CRS based interference measurements uses the latest subframe in therestricted subset as the reference resource (subject to the timingconstraint that the reference resource is at least four subframesearlier than the reporting subframe). This definition of referenceresource may not be adopted for resource-restricted measurements withCSI-RS based interference measurements (i.e. CSI-IM), since the sodefined subframe may not contain any CSI-RS configured for interferencemeasurements (i.e. CSI-IM resources). This can be resolved by modifyingthe reference resource as the latest CSI-RS bearing subframe in therestricted subset (also subject to the timing constraint that thereference resource is at least four subframes earlier than the reportingsubframe). The reference resource may be further restricted to be thelatest CSI-RS REs (as opposed to the subframe) in the restricted subset.

With regard to the number of CSI-IM configurations, since one CSI-IMconfiguration may span in only one subset of subframes, at least twoCSI-IM configurations may be used for interference measurements. Inaddition, more CSI-IM configurations may be used to prevent further“dilution” of CSI-IM resource density, thus improving the measurementaccuracy. If any of the CSI-IM configurations spans across bothrestricted subsets, each of the resource-restricted CSI reports islinked to the CSI-IM resources in only one subset and does not utilizeany CSI-RS resources in the other subset. A benefit of configuring a UEwith CSI-IM resource for interference measurement and withresource-restricted measurement (as opposed to configuring CSI-IMresource for interference measurement to effectively realizeresource-restricted measurement as mentioned above) is supporting amixture of Rel-10 UEs and Rel-11 and beyond UEs at the same time. Inother words, resource-restricted measurement based on subframe subsetsmay need to be configured for supporting Rel-10 UEs, and hence it may beuseful to configure Rel-11 UEs with subframe subsets as well on top oftheir CSI-IM resource based interference measurement. However, if thesupport of Rel-10 UEs is not needed, then the method of CSI-IM resourcebased interference measurement may be preferred to effectively realizeresource-restricted measurement for its high flexibility and morefunctionality.

FIG. 7 illustrates an embodiment of two interference measurement CSI-IMresources 700 configured and used for resource-restricted measurements,for example over 40 subframes. A first subset (subset 1) of interferencemeasurements can use all CSI-IM resources in subset 1 (including bothCSI-IM resource 1 and CSI-IM resource 2 in this example), and a secondsubset (subset 2) of interference measurements can use all CSI-IMresources in subset 2 (including both CSI-IM resource 1 and CSI-IMresource 2 in this example). However, not all subframes are used asreference resources. The interference measurements on CSI-IM resources 1and 2 in subset 1 are not necessarily used for a same CQI in subset 1.Similarly, the interference measurements on CSI-IM resources 1 and 2 insubset 2 are not necessarily used for a same CQI in subset 2.

The resource-restricted measurements based feedback may not besufficient for general CoMP schemes. The CoMP schemes with semi-staticcoordination may adopt resource-restricted measurements for the CSImeasurements and reporting, i.e., use the resource-restrictedmeasurements for interference measurements and CSI feedback. Compared toCoMP feedback without resorting to restricted subsets to realize thefunctionalities of resource-restricted measurements, the schemes withresource-restricted measurements have the advantage of lower complexitysince over one subset, the Macro does not need to “emulate” theinterference seen by Pico UEs over the other subset.

FIG. 8 illustrates embodiment resource-restricted measurements 800configured and used for CoMP schemes with semi-static coordination, suchas CBB. The CSI reports for a first subset (subset 1), on which theMacro performs normal transmission, use the CSI-IM in subset 1 forinterference measurements. The CSI reports for a second subset (subset2), on which the Macro avoids interfering certain or determined spatialdirections with or without reduced power, use the CSI-IM in subset 2 forinterference measurements.

In Release-11 and/or beyond, there are four scenarios described in TR36.819, which is incorporated herein by reference:

Scenario 1: Homogeneous network with intra-site CoMP;Scenario 2: Homogeneous network with high transmission power RemoteRadio Heads (RRHs);Scenario 3: Heterogeneous network with low power RRHs within themacrocell coverage where the transmission/reception points created bythe RRHs have different cell IDs as the macro cell;Scenario 4: Heterogeneous network with low power RRHs within themacrocell coverage where the transmission/reception points created bythe RRHs have the same cell IDs as the macro cell.

In scenario 4, a single shared cell-ID is used for multiple sites. Inthis case, cell-ID based transmission set configuration is notapplicable. CSI-RS based configuration can be used for scenario 4instead of cell-ID based configuration. For the multiple cell-IDs casein scenario 3, the UE may not need to know whether there is an actualcell corresponding to a CSI-RS pattern in order to use the CSI-RSpattern for PMI/CQI feedback measurement besides the signaled CSI-RSpattern. Even though there is another neighbor cell, the current cellcan borrow the antennas from the neighbor cell for data transmission ofUE within the current cell by directly informing a CSI-RS pattern ofantennas of neighbor cell to a UE, without the need to inform the UEthat there is a neighbor cell. By directly signaling the CSI-RS patternsto a UE, the UE doesn't need to blindly detect the signaling in neighborcells to use the CSI-RS patterns. Regardless of scenario 3 or scenario4, the eNB(s) or the network point(s) can signal to a UE one or multipleCSI-RS resources/patterns with same or different CSI-RS scramblingcodes, and hence the UE may or may not know (or may or may not need toknow) if the CSI-RS resources/patterns are associated with one eNB (ornetwork point) or multiple eNBs (or network points).

FIG. 9 illustrates an embodiment reception method 900 that can beimplemented at a UE as part of or to support the measurement and CSIconfiguration and feedback schemes and methods above. At step 901, thereceived signal (at the UE side) is transformed by FFT, and then turnedinto a frequency domain signal per OFDM symbol. At step 902, the UEdecodes the signaling from the eNB to obtain the CSI-RS. Using thisinformation, de-mapping is implemented at step 903 to obtain the CSI-RSsignal. At step 904, this CSI-RS signal is used for channel estimationand measurement, where the CSI-RS signal is estimated based on theCSI-RS signal.

In Rel-10, a scramble code is determined using a slot number and acell-ID, e.g., an initial phase of a Gold sequence is determined by theslot number and cell-ID. This scrambling code generation scheme may beused in the method 900, since the CSI-RS may be borrowed from neighborcells. Hence, in the signaling of the CSI-RS, the subframe number orslot number is also indicated (to the UE), e.g., assuming that not allthe CSI-RSs have an aligned slot number to generate scrambling code. Forinstance, a subframe shift is used for a cell to avoid interference ofPBCH between the cell and neighbor cells. Hence, the UE needs to knowthe subframe or slot number to generate the CSI-RS scrambling code.

In case of actual deployment, two cells may have time domainmultiplexing (TDM) CSI-RS patterns in different subframes instead of FDMCSI-RS patterns. Thus, some but not all neighbor cells in the CoMP setuse the same subframe for their CSI-RS. For example, in case of theHetNet scenario, two sets of CSI-RS ports in different subframes may bedefined for interference measurement and two CQI/PMI feedbacks may bemeasured and reported independently. Hence, in the signaling of CSI-RS,the signaling may include a duty cycle and an offset for each subset ofCSI-RS ports (or each CSI-RS pattern) to support defining multiple TDMedsets of CSI-RS ports. The interference measurement may be signaled.However, two CSI-RS patterns may be located in different subframes, andhence the interference may be different in different subframes. As such,a signaling may indicate a set of CSI-RS for interference measurement.This set of CSI-RS for interference measurement may be a subset of theCSI-RS signaled for CQI/PMI/RI or RRM/RLM measurement.

Furthermore, in neighbor cells, zero-power CSI-RS may be configured,e.g., muting for PDSCH is adopted and some cells' interference is muted.Hence, not every CSI-RS is used to measure the interference. To enablemeasurement of the interference of a cell, muting is not adopted forthat cell for the CSI-RS for interference measurement. The signaling ofCSI-RS may include information indicating CSI-RS for interferencemeasurement as described above. Multiple sets of CSI-RSs forinterference measurement may be signaled, which may be based on TDM,frequency domain multiplexing (FDM), or code division multiplexing(CDM). The CSI-RS for interference measurement may be a non-zero-powerCSI-RS, a zero-power CSI-RS, or includes both zero-power CSI-RS andnon-zero-power CSI-RS. The signaling of CSI-RS can be applied forzero-power CSI-RS and also non-zero-power CSI-RS.

In an embodiment, the signaling for CSI-RS includes a subframe numberand/or slot number, a scrambling code, some indication on interferencemeasurement, an indication of RRM/RLM measurement or CQI/PMI/RImeasurement, a duty cycle and offset for each CSI-RS pattern or eachsubset of CSI-RS ports, or combinations thereof. Multiple sets of CSI-RSfor interference measurement may be signaled and used. The CSI-RSsignaling may indicate a subset of CSI-RS for interference measurementusing a bitmap method based on a signaled set of CSI-RS ports.

In the case of a NZP CSI-RS configuration, according to the RAN1#67 forRel-11, the configuration of each non-zero-power CSI-RS resourceincludes a configurable parameter to derive the pseudo-random sequencegenerator initialization (c_(init)). The parameter c_(init) isindependently configured among CSI-RS resources, such that

c _(init)=2¹⁰·(7·(n _(s)+1)+l+1)·(2·X+1)+2·X·N _(CP),

where X is configurable in a UE-specific manner and may take on anyvalue in the range of 0 to 503. In Rel-10, the pseudo-random sequencegenerator may be initialized at the start of each OFDM symbol withc_(init)=2¹⁰·(7·(n_(s)+1)+l+1)·(2·N_(ID) ^(cell)+1)+2·N_(ID)^(cell)+N_(CP). Considering the application of CoMP without carrieraggregation for simplicity, the cell ID is derived by the UE accordingto the primary cell.

If the initialization is performed as in Rel-10 when a UE receives RRCsignaling with the configuration of multiple non-zero-power CSI-RSresources, then all CSI-RS ports in all the non-zero-power CSI-RSresources may be assumed by the UE to be scrambled by the same sequenceassociated with the primary cell. This is in a scenario with CoMPtransmission points belonging to different cells. If the initializationis performed flexibly with parameter X independently configurable perCSI-RS resource and assuming one value of X per CSI-RS resource, theneach CSI-RS resource can be associated with a different sequence. Thus,the CSI-RS ports sent from a transmission point belonging to aparticular cell can be scrambled by the sequence associated with thiscell, and not the primary cell of the UE.

In one example, the CoMP measurement set comprises 3 transmissionpoints, each belonging to a different cell. Additionally, the networkcomprises a mixture of Rel-11 and Rel-10 UEs that rely on CSI-RS forfeedback. Each transmission point (TP) provides the UEs with CSI-RS forCSI feedback. Rel-10 UEs assume that CSI-RS ports are scrambled with asequence initialized according to the cell identity of their respectiveprimary cell. Therefore, each TP sends one CSI-RS resource withscrambling according to Rel-10. In addition, each TP sends one CSI-RSresource for CoMP measurements by Rel-11 UEs located in the twocooperating cells. With the flexible configuration of parameter X, thesame CSI-RS resource as for Rel-10 UEs can be reused by Rel-11 UEs. Withthe inflexible configuration according to Rel-10, each transmissionpoint sends two additional CSI-RS resources with the same ports as theCSI-RS resource configured for Rel-10 UEs, where each CSI-RS resource isscrambled with the cell identity of each of the two cooperating cells.

In the formula of initial value for pseudo-random sequence generator,the initial value depends on the slot number n_(s) where the CSI-RSresource is present and the slot number n_(s) in a frame ranges from 0to 19. The UE can detect the slot number of the serving cell based on ashared channel (SCH) channel. When multiple CSI-RS in a subframe havethe same slot number, there is no need to inform the slot number togenerate the pseudo-random sequence for multiple CSI-RS. However, if aCSI-RS resource is transmitted by a neighbor cell, which has aslot/subframe shifting relative to the serving cell, then the CSI-RSresource of the neighbor cell may not have the same slot number as theserving cell. Therefore, information about the slot number is indicatedper CSI-RS resource. For example, in case of scenario 3 above, there maybe a slot or subframe shift between two cells to avoid interference dueto PBCH, PCH, etc.

The subframe-level shifting can be used to offer adequate interferenceprotection in HetNet. Therefore, the eNB can provide the additionalsignaling of subframe offset D_(n) per non-zero-power CSI-RS resource,as follows:

c _(init)=2¹⁰·(7·((n _(s) +D _(ns))mod 20+1)+l+1)·(2·X+1)+2·X+N _(CP),

where X is configurable in a UE-specific manner, X may take on any valuein the range of 0 to 503, D_(ns) is relative to subframe 0 of theserving cell, and n_(s) is the slot number of the serving cell derivedby the UE.

To support coherent joint transmission in Rel-11, and improveflexibility, inter-CSI-RS-resource phase information may be reportedalong with per-CSI-RS-resource PMI. Alternatively, one PMI may bereported relative to all the ports in multiple CSI-RS resources. Thisapproach may be referred to as “CSI aggregated across multiple CSI-RSresources”. This approach has two drawbacks if no new codebook isspecified. The first drawback is that the PMI size is limited to 2, 4 or8. The second drawback is that the inter-point phase information cannotbe further optimized and is constrained by the Rel-8 and Rel-10codebooks. This approach also requires signaling to inform the UE toaggregate multiple CSI-RS resources into a single PMI. Since the UE isalso expected to support per-CSI-RS-resource PMI feedback, the signalingfor switching between the two types of feedback is required. Theaggregated CSI across multiple transmission points may not besufficiently efficient for supporting coherent joint transmission inRel-11.

In an embodiment, to support one PMI across multiple transmissionpoints, multiple transmission points are aggregated into a single CSI-RSresource, which may avoid the extra signaling for switching withper-CSI-RS-resource CSI feedback. In shared cell ID scenarios, it isstraightforward or relatively simple to aggregate CSI-RS ports sent bydifferent points that share the same cell ID within one CSI-RS resource,and thus initialize the sequence for all CSI-RS ports with the same cellID.

In scenarios 1, 2 and 3 above where transmission points belong todifferent cells, aggregating CSI-RS ports within the same CSI-RSresource may require configuring independently the scramblinginitialization for each port within the same CSI-RS resource. OtherwiseCSI-RS overhead is sacrificed due to the requirement to support Rel-10UEs. In one implementation, the CoMP measurement set comprises 2transmission points, each belonging to a different cell. Additionally,the network comprises a mixture of Rel-11 and Rel-10 UEs that rely onCSI-RS for feedback. The scrambling initialization is independent perCSI-RS resource, where the sequence per port is independent within aCSI-RS resource or the same sequence is adopted for all ports within aCSI-RS resource.

The lack of flexibility to configure CSI-RS ports with differentsequences within one CSI-RS resource incurs more overhead. In anembodiment, if the support of inter-CSI-RS resource phase feedback isnot specified in Rel-11, the network has the capability to configureCSI-RS ports with different sequences within a CSI-RS resource tosupport coherent joint transmission. If inter-CSI-RS-resource phasefeedback is not specified, CSI-RS ports can be configured to havedifferent sequences within a CSI-RS resource, i.e., X is configurableindependently per CSI-RS port.

FIG. 10 is a block diagram of a processing system 1000 that can be usedto implement various embodiments. Specific devices may utilize all ofthe components shown, or only a subset of the components, and levels ofintegration may vary from device to device. Furthermore, a device maycontain multiple instances of a component, such as multiple processingunits, processors, memories, transmitters, receivers, etc. Theprocessing system 1000 may comprise a processing unit 1001 equipped withone or more input/output devices, such as a speaker, microphone, mouse,touchscreen, keypad, keyboard, printer, display, and the like. Theprocessing unit 1001 may include a central processing unit (CPU) 1010, amemory 1020, a mass storage device 1030, a video adapter 1040, and anI/O interface 1050 connected to a bus. The bus may be one or more of anytype of several bus architectures including a memory bus or memorycontroller, a peripheral bus, a video bus, or the like.

The CPU 1010 may comprise any type of electronic data processor. Thememory 1020 may comprise any type of system memory such as static randomaccess memory (SRAM), dynamic random access memory (DRAM), synchronousDRAM (SDRAM), read-only memory (ROM), a combination thereof, or thelike. In an embodiment, the memory 1020 may include ROM for use atboot-up, and DRAM for program and data storage for use while executingprograms. The mass storage device 1030 may comprise any type of storagedevice configured to store data, programs, and other information and tomake the data, programs, and other information accessible via the bus.The mass storage device 1030 may comprise, for example, one or more of asolid state drive, hard disk drive, a magnetic disk drive, an opticaldisk drive, or the like.

The video adapter 1040 and the I/O interface 1060 provide interfaces tocouple external input and output devices to the processing unit. Asillustrated, examples of input and output devices include a display 1060coupled to the video adapter 1040 and any combination ofmouse/keyboard/printer 1070 coupled to the I/O interface 1060. Otherdevices may be coupled to the processing unit 1001, and additional orfewer interface cards may be utilized. For example, a serial interfacecard (not shown) may be used to provide a serial interface for aprinter.

The processing unit 1001 also includes one or more network interfaces1050, which may comprise wired links, such as an Ethernet cable or thelike, and/or wireless links to access nodes or one or more networks1080. The network interface 1050 allows the processing unit 1001 tocommunicate with remote units via the networks 1080. For example, thenetwork interface 1050 may provide wireless communication via one ormore transmitters/transmit antennas and one or more receivers/receiveantennas. In an embodiment, the processing unit 1001 is coupled to alocal-area network or a wide-area network for data processing andcommunications with remote devices, such as other processing units, theInternet, remote storage facilities, or the like.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,compositions of matter, means, methods, or steps, presently existing orlater to be developed, that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufacture, compositions of matter,means, methods, or steps.

What is claimed is:
 1. A method for operating a user equipment (UE), themethod comprising: receiving, by the UE from a network, a firstsignaling configuring a plurality of non-zero power (NZP) channel stateinformation reference signal (CSI-RS) resources, each NZP CSI-RSresource is associated with an index; receiving, by the UE from thenetwork, a second signaling indicating a first subset of a plurality ofNZP CSI-RS resource indices allocated for channel measurement; andreceiving, by the UE from the network, a third signaling indicating asecond subset of the plurality of NZP CSI-RS resource indices allocatedfor interference measurement.
 2. The method of claim 1, wherein thesecond signaling and the third signaling are received in a singletransmission.
 3. The method of claim 2, wherein the first signaling, thesecond signaling, and the third signaling are received in the singletransmission.
 4. The method of claim 2, wherein the second signaling andthe third signaling are the same signaling.
 5. The method of claim 1,wherein the second signaling and the third signaling are received indifferent transmissions.
 6. The method of claim 1, further comprisingreceiving, by the UE from the network, a fourth signaling indicating oneor more zero power (ZP) CSI-RS resource indices allocated forinterference measurement.
 7. The method of claim 6, further comprising:receiving, by the UE from the network, a fifth signaling indicating atleast one channel state information (CSI) report configuration eachassociated with a CSI report configuration index; generating, by the UE,a CSI report in accordance with NZP CSI-RS resource elements (REs)corresponding to a first NZP CSI-RS resource configuration associatedwith the first subset and at least one of a second NZP CSI-RS resourceconfiguration associated with the second subset or ZP CSI-RS REscorresponding to a ZP CSI-RS resource configuration associated with theone or more ZP CSI-RS resource indices allocated for interferencemeasurement, wherein the first subset and the at least one of the secondsubset or the ZP CSI-RS REs corresponding to the ZP CSI-RS resourceconfiguration associated with the one or more ZP CSI-RS resource indicesallocated for interference measurement are associated with one of the atleast one CSI report configuration; and sending, by the UE to thenetwork, the CSI report.
 8. The method of claim 7, wherein the CSIreport is generated for a first subframe that is at least a pre-definednumber of subframes earlier than a reporting subframe.
 9. The method ofclaim 7, wherein the association between the first subset and the secondsubset and the one of the at least one CSI report configuration isreceived in one of the second signaling, the third signaling, or channelquality indication (CQI) signaling.
 10. A method for operating a device,the method comprising: sending, by the device to a user equipment (UE),a first signaling indicating a plurality of non-zero power (NZP) channelstate information reference signal (CSI-RS) resources, each NZP CSI-RSresource is associated with an index; sending, by the device to the UE,a second signaling indicating a first subset of a plurality of NZPCSI-RS resource indices allocated for channel measurement; and sending,by the device to the UE, a third signaling indicating a second subset ofthe plurality of NZP CSI-RS resource indices allocated for interferencemeasurement.
 11. The method of claim 10, wherein the second signalingand the third signaling are sent in a single transmission.
 12. Themethod of claim 10, wherein the first signaling, the second signaling,and the third signaling are sent in a single transmission.
 13. Themethod of claim 10, wherein the second signaling and the third signalingare sent in different transmissions.
 14. The method of claim 10, furthercomprising sending, by the device to the UE, a fourth signalingindicating one or more zero power (ZP) CSI-RS resource indices allocatedfor interference measurement.
 15. The method of claim 10, furthercomprising sending, by the device to the UE, a fifth signalingindicating at least a channel state information (CSI) reportconfiguration associated with a CSI report configuration index.
 16. Themethod of claim 15, further comprising receiving, by the device from theUE, a CSI report.
 17. A method for operating a user equipment (UE), themethod comprising: receiving, by the UE from a network, a firstsignaling indicating a plurality of channel state information referencesignal (CSI-RS) resource indices allocated for communications; andreceiving, by the UE from the network, a second signaling indicating asubset of the plurality of CSI-RS resource indices for radio linkmeasurement.
 18. The method of claim 17, wherein the first signaling andthe second signaling are received in a single transmission.
 19. Themethod of claim 17, wherein the first signaling and the second signalingare received in different transmissions.
 20. The method of claim 17,wherein the subset of the plurality of CSI-RS resource indices for radiolink measurement is associated with a single radio link measurementreference signal (RLM-RS).
 21. A method for operating a device, themethod comprising: sending, by the device to a user equipment (UE), afirst signaling indicating a plurality of channel state informationreference signal (CSI-RS) resource indices allocated for communications;and sending by the device to the UE, a second signaling indicating asubset of the plurality of CSI-RS resource indices for radio linkmeasurement.
 22. The method of claim 21, wherein the first signaling andthe second signaling are sent in a single transmission.
 23. The methodof claim 21, wherein the first signaling and the second signaling aresent in different transmissions.
 24. The method of claim 21, wherein thesubset of the plurality of CSI-RS resource indices for radio linkmeasurement is associated with a single radio link measurement referencesignal (RLM-RS).
 25. A user equipment (UE) comprising: one or moreprocessors; and a computer readable storage medium storing programmingfor execution by the one or more processors, the programming includinginstructions to configure the UE to: receive, from a network, a firstsignaling indicating a plurality of non-zero power (NZP) channel stateinformation reference signal (CSI-RS) resources, each NZP CSI-RSresource is associated with an index, receive, from the network, asecond signaling indicating a first subset of a plurality of NZP CSI-RSresource indices allocated for channel measurement, and receive, fromthe network, a third signaling indicating a second subset of theplurality of NZP CSI-RS resource indices allocated for interferencemeasurement.
 26. The UE of claim 25, wherein the programming includesinstructions to configure the UE to receive the second signaling and thethird signaling in a single transmission.
 27. The UE of claim 26,wherein the programming includes instructions to configure the UE toreceive the first signaling, the second signaling, and the thirdsignaling in the single transmission.
 28. The UE of claim 25, whereinthe programming includes instructions to configure the UE to receive thesecond signaling and the third signaling in different transmissions. 29.The UE of claim 25, wherein the programming includes instructions toconfigure the UE to receive, from the network, a fourth signalingindicating one or more zero power (ZP) CSI-RS resource indices allocatedfor interference measurement.
 30. The UE of claim 25, wherein theprogramming includes instructions to configure the UE to receive, fromthe network, a fifth signaling indicating at least one channel stateinformation (CSI) report configuration associated with a CSI reportconfiguration index, generate a CSI report in accordance with NZP CSI-RSresource elements (REs) corresponding to a first NZP CSI-RS resourceconfiguration associated with the first subset of the plurality of NZPCSI-RS resource indices allocated for channel measurement and a secondNZP CSI-RS resource configuration associated with the second subset ofthe plurality of NZP CSI-RS resource indices allocated for interferencemeasurement, wherein the first subset of the plurality of NZP CSI-RSresource indices allocated for channel measurement and the second subsetof the plurality of NZP CSI-RS resource indices allocated forinterference measurement are associated with one of the at least one CSIreport configuration, and send, to the network, the CSI report.
 31. Adevice comprising: one or more processors; and a computer readablestorage medium storing programming for execution by the one or moreprocessors, the programming including instructions to configure thedevice to: send, to a user equipment (UE), a first signaling indicatinga plurality of non-zero power (NZP) channel state information referencesignal (CSI-RS) resources, each NZP CSI-RS resource is associated withan index, send, to the UE, a second signaling indicating a first subsetof a plurality of NZP CSI-RS resource indices allocated for channelmeasurement, and send, to the UE, a third signaling indicating a secondsubset of the plurality of NZP CSI-RS resource indices allocated forinterference measurement.
 32. The device of claim 31, wherein theprogramming includes instructions to configure the device to send thesecond signaling and the third signaling in a single transmission. 33.The device of claim 31, wherein the programming includes instructions toconfigure the device to send the second signaling and the thirdsignaling in different transmissions.
 34. The device of claim 31,wherein the programming includes instructions to configure the device tosend, to the UE, a fourth signaling indicating one or more zero power(ZP) CSI-RS resource indices allocated for interference measurement.